Structure and Function of Frizzled-Like Proteins in Skeletal Development

Frzb是一种分泌蛋白，最初从 纯化的软骨提取物，并与富含半胱氨酸的 结构域（CRD）的卷曲，Wnt受体。Wnt蛋白是 分泌的信号分子具有许多发育 功能，包括骨骼发育，以及 肿瘤发生最近的研究表明，Frzb可以结合， 这导致人们猜测潜在的治疗方法 这种活性在修饰Wnt诱导的发育和 致癌事件。我们已经证明，Frzb是暂时的， 并在骨骼和颅面 发展为了理解Frzb在 骨骼发育我们正在进行一个条件基因 敲除，使用Cre-LoxP重组系统。我们 目前正在分析创始小鼠的生殖系传播， “floxed”Frzb基因。一旦确认，我们将通过“floxed” 小鼠与普遍表达Cre的小鼠品系。卵内 细菌酶Cre重组酶的表达将导致 CRD编码外显子的切除导致Frzb缺失 功能如果这产生了一个致命的表型， 发展，然后我们将交叉的“floxed”小鼠与转基因 在肢体特异性启动子控制下表达Cre的细胞系。 对Frzb调控元件的分析将提供有用的 关于控制其时间和空间表达的信息 格局我们对小鼠Frzb进行了表征，并确定其 外显子/内含子结构。瞬时转基因实验， 正在进行各种启动子序列测定， 组织特异性调节区的位置。

Frzb is a secreted protein initially isolated from purified cartilage extracts and shares homology to the cysteine rich domain (CRD) of frizzled, a Wnt receptor. Wnt proteins are secreted signaling molecules having numerous developmental functions, including skeletal development, as well as dysfunction in oncogenesis. It was recently shown that Frzb can bind to and inactivate Wnts, leading to speculation for the potential therapeutic use of such activity in modifying Wnt induced developmental and oncogenic events. We have demonstrated that Frzb is temporally and spatially expressed during skeletal and craniofacial development. In an attempt to understand the role of Frzb in skeletal development we are conducting a conditional gene knockout, using the Cre-LoxP recombination system. We are currently analyzing founder mice for germline transmission of the "floxed" Frzb gene. Once confirmed we shall cross the "floxed" mice with a ubiquitously expressing Cre mouse line. In ovo expression of the bacterial enzyme Cre recombinase will result in the excision of the CRD encoding exon resulting in a loss of Frzb function. Should this produce a lethal phenotype, early in development, we will then cross the "floxed" mice with a transgenic line expressing Cre under the control of a limb-specific promoter. Analysis of the regulatory elements of Frzb will provide useful information as to the control of its temporal and spatial expression pattern. We have characterized mouse Frzb and determined its exon/intron structure. Transient transgenic experiments using various promoter sequences are being conducted to determine the location of the tissue-specific regulatory regions.